Cancer remains one of the major modern day health issues and accounts for a large proportion of health and hospital costs. For example, in excess of 106,000 new cases of large bowel cancer are diagnosed each year in the United States alone. Of these, about 65,230 cases are colon cancer while the remainder of patients have cancer of the rectum. In the United States, approximately 49,920 people die from colorectal cancer (CRC) yearly, with about 1 in 17 people developing CRC during some stage of their life.
Surgery is the mainstay of care for CRC. Radiotherapy (for rectal cancer) and/or chemotherapy can also be administered. About 60% of rectal cancer patients have surgery as well as both radiotherapy and chemotherapy. Surgery involves resection of the affected region and rejoining of the bowel forming an anastomosis. Commonly, a colostomy involving attaching the top end of the colon to an opening (known as a stoma) made in the abdomen is performed to divert faecal matter away from the anastomosis to a collection bag arranged externally of the patient's body while the anastomosis is healing. Connection of the lower end of the small intestine (the ileum) to the stoma is known as an ileostomy. The colostomy or ileostomy is usually temporary requiring a subsequent reversal operation to be performed.
A patient who has a rectal cancer, for example, may have a Lower Anterior Resection (LAR). Of such patients in the United States, about 32% will undergo a temporary diverting loop ileostomy. A patient that has an LAR but not an ileostomy has a 10-30% risk of having an anastomotic leak which can be either symptomatic (10-15%) or asymptomatic. However, patients that suffer anastomotic leakage not only then require an ileostomy, an abscess can form at the site of the leakage which then requires drainage, involving a yet further operation complicating the healing process. If the leakage is symptomatic the mortality rate is 6-22%.
The average time to surgical reversal of a colostomy or ileostomy is about 15 to 23 weeks. Immediately prior to the reversal, a contrast (e.g., barium) enema is performed to ensure that the anastomosis has healed. A routine reversal is not without its own risks, with the overall complication rate (e.g., wound infection etc) estimated at about 19.8%. About 3% of patients suffer an anastomotic leak associated with the reversal operation. Moreover, in the United States, the financial cost for the colostomy or ileostomy and subsequent reversal can be US$10,000 to $15,000 or more per patient.
As such, not only is there significant morbidity and mortality associated with anastomotic leakage arising from primary surgery for treatment of CRC, the risk of leakage is compounded by subsequent diverting colostomy/ileostomy procedures and reversal operations where performed, the latter treatments adding significantly to the financial burden involved in obtaining treatment.
The application of sub-atmospheric pressure to acute or chronic wounds to promote wound healing is known as negative pressure wound therapy (NPWT) or vacuum assisted closure (VAC). VAC therapy involves creating a negative-pressure in the local wound environment, drawing away bacteria, exudate, fluid and desiccated tissue from the wound site. Besides improving localised conditions and reducing oedema for wound healing, the negative pressure may draw wound edges together and increase the rate of healing by promoting blood flow and facilitating localised cell migration and proliferation. Indeed, it is believed VAC therapy can increase the rate of wound closure.
Conventionally, VAC therapy has been applied to wounds in the skin such as burns, grafts, surgical incisions, diabetic ulcers, pressure ulcers, venous stasis ulcers and wounds arising from trauma. These “wound VAC” devices comprise a pad of open-cell sponge like material or a porous mat for being placed on the wound. A vacuum is applied to the sponge via a drainage tube through which fluid and exudate from the wound that is drawn into the sponge or mat is drained away. A drape can be laid over the sponge or porous mat to facilitate sealing of the wound. Such devices are commercially available and, for example, are described in U.S. patent application Ser. Nos. 11/186,056, 11/347,073, 11/409,116, 11/268,212, 12/233,211, and International Patent Application WO 93/09727. In more recent times, VAC devices comprising like porous sponges and mats have been used to drain seromas and fluids from internal bodily spaces following surgery and to facilitate the healing of wounds on outer surfaces of internal body organs and tissues, examples of which are described in WO 03/028786, U.S. Pat. No. 5,437,651 and patent application Ser. No. 11/646,918.